Pens, pencils, and other writing instruments have been evolving with the history of mankind. With the advent of chemical technologies of synthesizing inks and dyes, current writing instruments allow an user to write or draw in numerous colors of his or her choice. Such writing instruments may be categorized into two groups based on physical characteristics of marking substances employed thereby, e.g., those employing volatile, less volatile or nonvolatile marking substances.
When the volatile marking substances are employed, they continuously evaporate through tips of such writing instruments and tend to form deposits or chunks of inks or dyes on such tips, which not only interfere with normal operation of the instruments but also shorten their life span. In order to prevent such evaporation, all conventional writing tools using such volatile marking substances come with caps capable of being disposed over and removed from the tips so that an user may remove the caps from the tips and write or draw. After use, the user may then put such caps back over the tips to enclose such tips and to prevent evaporation of the marking substances therethrough. Because such caps are generally provided as separate articles, the user has to keep track of whereabouts of such caps while he or she uses the writing instruments. When the caps are lost, the user has to find other caps or to ditch the entire instruments. In order to overcome this inconvenience, some caps are coupled to such instruments by string, chains, strips or other conventional couplers. Other caps are coupled to the instruments by forming unitary articles therewith. Regardless of detailed configurations thereof, such writing instruments still mandate the user to remove the caps before she or he uses the tools and to put the caps back after she or he is done with writing or drawing.
Compared with less- or nonvolatile marking substances, volatile marking substances generally employ water or volatile solvents as their base and includes inks or dyes mixed or suspended therein. In addition, such volatile marking substances tend to be applied through thicker and/or wider tips of the instruments for underlining or coloring purposes. Accordingly, conventional writing instruments using the volatile marking substances tend to last a shorter period of life than those tools using the less- or nonvolatile substances. For this reason, the conventional instruments generally has a single cartridge containing such a volatile marking substance and a single tip dispensing a single color, thus requiring the user to carry several different tools when she or he wants to mark or underline in several colors.
Multicolor writing instruments have been in use since 1950's. For example, some instruments include multiple sidebars each assigned to a different cartridge containing a marking substance with a different color, and others employ a case which rotates or otherwise moves along multiple directions each arranged to actuate a different cartridge. However, these multicolor writing instruments have been developed solely for those cartridges containing the less- or nonvolatile marking substances.
Accordingly, there is a strong need for multicolor writing tools which incorporate various cap members capable of exposing tips of different cartridges one at a time during use and then enclosing the tips before or after use for the purpose of minimizing evaporation of such substances through the tips. More importantly, there also is an urgent need for the multicolor writing tools capable of opening and closing the cap member by other parts of the tools, thereby obviating the user from engaging in a separate maneuver of manipulating such a cap member.